1. Field of the Invention
The present invention relates to a magnetic head used in magnetic recorders, e.g., video tape recorders (VTR), digital video cassettes (DVC), digital audio tape recorders.
2. Related Art
An existing magnetic head used in VTRs has a configuration as shown in FIG. 6.
A magnetic head 1 shown in FIG. 6 is a so-called ferrite bulk magnetic head which consists of a pair of ferrite cores. Namely, the head is formed by bonding together a C-type core 2 and a C-type core 3 by bonding glass 4 while they are positioned so as to be opposite to each other, whereby a gap 5 is formed so as to have a predetermined width. A coil (not shown) is wound around winding grooves 2a, 3a formed in respective cores 2, 3.
More specifically, as shown in FIG. 7, track width regulating grooves 2b, 3b are formed in both side surfaces of the cores 2, 3 so that the gap 5 can be formed to have a desired width. The track width regulating grooves 2b, 3b are filled with the bonding glass 4 the instant the cores 2, 3 are butt-joined together.
A tape slide surface A is defined in such a way that the gap 5 formed between the track width regulating grooves 2b, 3b is surrounded by the upper surfaces of the cores 2, 3 and the upper surface of the bonding glass 4.
There are also known so-called MIG (Metal-in-Gap) magnetic heads having a construction as shown in FIG. 8.
In FIG. 8, a MIG magnetic head 6 is comprised of a pair of Mn-Zn ferrite C-type cores 7, 8. Surfaces of the C-type cores 7, 8 to be butt-joined are coated with magnetic metal films 7a, 8a, and the surfaces are bonded by the bonding glass 4 while they are opposite to each other, whereby a gap 9 having a predetermined width is formed. A coil (not shown) is wound around each of winding grooves 7b, 8b formed in the respective C-type cores 7, 8.
More specifically, as shown in FIG. 9, track width regulating grooves 7c, 8c are formed in both side surfaces of the C-type cores 7, 8 so that the gap 9 can be formed to have a desired width. Magnetic metal films 7a, 8a are formed on the surfaces of the C-type cores 7, 8 to be butt-joined, and the track width regulating grooves 7c, 8c are filled with the bonding glass 4 the instant the C-type cores 7, 8 are butt-joined together.
A tape slide surface A is defined in such a way that the gap 9 formed between the track width regulating grooves 7c, 8c is surrounded by the upper surfaces of the C-type cores 7, 8 and the upper surface of the bonding glass 4.
Both types of magnetic heads 1, 6 present the following problems.
With regard to the magnetic heads 1, 6, the C-type cores 3, 8 have comparatively large widths, so that the magnetic heads 1, 6 have large inductance. Further, the tape slide surface is made up of the C-type cores 2, 3 or 7, 8 consisting of, e.g., ferrite, and hence it is abraded to a comparatively large extent. As a result, the recording/playback characteristics of the magnetic head are deteriorated.
The C-type cores 2, 3 or 7, 8 are joined together after the track width regulating grooves 2b, 3b or 7c, 8c have been formed. Therefore, as shown in FIG. 7 or 9, the track width regulating grooves 2b, 3b or 7c, 8c of the C-type cores 2, 3 or 7, 8 are shifted from each other. Leakage of the magnetic flux occurring in a track deviation "d" may cause noise when the magnetic head 1 or 6 carries out recording or playback, thereby obstructing correct recording or playback of a signal. Particularly, a magnetic head having a narrow track width, such as a DVC, has the risk of being unable to effect recording or playback by the track deviation "d."